package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    //阻塞队列
    private BlockingQueue<VoucherOrder> ordersTask  = new ArrayBlockingQueue<>(1024*1024);
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    private class VoucherOrderHandler implements Runnable{

        @Override
        public void run() {
            while(true){
                try {
                    //1.获取队列中中的订单信息
                    VoucherOrder voucherOrder = ordersTask.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常",e);
                }
            }
        }
    }

    /**
     * 创建订单
     * @param voucherOrder
     */
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //获取用户
        Long userId = voucherOrder.getUserId();
//        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order" + userId);

        //尝试获取锁
        boolean flag = lock.tryLock();
        if(!flag){
            //获取锁失败
            log.error("不允许重复下单");
            return;
        }
        try{
            //获取锁成功
            currentProxy.createVoucherOrder(voucherOrder);
        }finally {
            //释放锁
            lock.unlock();
        }
    }

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;//lua脚本
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();//初始化
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));//注入脚本在位置
        SECKILL_SCRIPT.setResultType(Long.class);//返回值类型
    }
    /**
     * 优惠券秒杀
     * @param voucherId 优惠券id
     * @return
     */
    private IVoucherOrderService currentProxy;
    @Override
    public /**synchronized**/ Result  seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        //2.判断结果是否为零
        int r = result.intValue();
        if(r != 0){
            //2.1不为零 没有购买资格
            return Result.fail(r==1 ? "库存不足":"不能重复下单");
        }
        //2.2为零 有购买资格 吧下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4.用户id
        voucherOrder.setUserId(userId);
        // 2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6.放入阻塞队列
        ordersTask.add(voucherOrder);
        //3.获取代理对象
         currentProxy = (IVoucherOrderService) AopContext.currentProxy();

        return Result.ok(orderId);

    }
    /*@Override
    public *//**synchronized**//* Result  seckillVoucher(Long voucherId) {
        //1.查询优惠券
        SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId);
        //2.判断秒杀是否开始
        if(seckillVoucher.getBeginTime().isAfter(LocalDateTime.now())){
            //尚未开始
            return Result.fail("秒杀尚未开始");
        }
        //3.判断秒杀是否已经结束
        if(seckillVoucher.getEndTime().isBefore(LocalDateTime.now())){
            //秒杀已经结束
            return Result.fail("秒杀已经结束");
        }
        //4.判断库存是否充足
        if (seckillVoucher.getStock()<1) {
            //库存不足
            return Result.fail("库存不足");
        }

        Long userId = UserHolder.getUser().getId();
//        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order" + userId);

        //尝试获取锁
        boolean flag = lock.tryLock();
        if(!flag){
            //获取锁失败
            return Result.fail("不允许重复下单");

        }
        try{
            //获取锁成功
            //获取代理对象
            IVoucherOrderService currentProxy = (IVoucherOrderService) AopContext.currentProxy();
            return currentProxy.createVoucherOrder(voucherId);
        }finally {
            //释放锁
            lock.unlock();
        }

//        synchronized (userId.toString().intern()){
//            //获取代理对象
//            IVoucherOrderService currentProxy = (IVoucherOrderService) AopContext.currentProxy();
//            return currentProxy.createVoucherOrder(voucherId);
//        }

    }*/

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        /*//5.一人一单
        Long userId = voucherOrder.getUserId();
        //5.1 查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //5.2 判断是否存在
        if(count>0){
            //用户已近购买过了
            return;
        }*/
        //6.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")//set stock = stock -1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock",0)//使用乐观锁解决超卖问题 where id =？ and stock > 0
                .update();
        if(!success){
            //扣减失败
            return;
        }
        //创建订单到数据库
        save(voucherOrder);
    }
}
